HAL ADC How to Use

group ADC_How_To_Use

How to use the ADC HAL module driver

HAL ADC driver usage

• ADC configuration

  • System configuration (out of HAL ADC driver)

    • RCC to provide ADC kernel clock

    • GPIO to connect ADC channels to device pins (if ADC usage with channel other than internal ones)

    • CPU Cortex NVIC to configure interrupts lines (if ADC usage with interrupt)

    • DMA channel (if ADC usage with data transfer by DMA)

  • ADC peripheral configuration

    • ADC peripheral is structured in subblocks with each a specific scope. HAL ADC follows this structure with a configuration structure and associated function for each subblock.

      • Mandatory subblocks, all must be configured:

        • ADC instance

        • ADC channel

      • Mandatory subblocks, at least one must be configured:

        • ADC group regular (prefix REG): main group available on all STM32 series, all ADC instances. Intended for regular data stream.

        • ADC group injected (prefix INJ): alternate group, availability depending on STM32 series and ADC instances. Intended for occasional or priority conversions.

      • Optional subblocks

        • Analog watchdog

        • Oversampling

        • Offset

        • Multimode (prefix MM): encompass multiple ADC instances (one master, some slaves) for synchronized operation.

    • ADC instances can belong to an ADC common instance, in this case they can share features (clock configuration, multimode capability, …). HAL ADC driver provides a mechanism to link HAL ADC handles and manage shared features.

  • HAL ADC configuration steps:

    1. Configure system

    2. Initialize HAL ADC handle using HAL_ADC_Init()

    3. Case of multiple ADC instances used: Link HAL ADC handles using HAL_ADC_SetLinkNextHandle() (for more details, refer to function description).

    4. Configure ADC subblocks using functions HAL_ADC_[INJ|REG|MM]_SetConfig{Features}()

• ADC operation

  • Activation and deactivation

    • ADC peripheral requires a specific procedure for activation (internal analog circuitry control, delay for stabilization time). Note: From activation step, ADC internal analog hardware is enabled, inducing current consumption. Therefore, after ADC usage, ADC must be deactivated for power optimization.

  • Calibration

    • ADC conversion accuracy can be improved by running a self calibration.

  • ADC conversions management

    • Conversions can be performed using three programming models:

      • Polling mode (blocking): using HAL_ADC_[INJ|REG|MM]_StartConv(), HAL_ADC_[INJ|REG|MM]_PollForConv()

      • Interrupt mode: using HAL_ADC_[INJ|REG|MM]_StartConv_IT(), HAL_ADC_IRQHandler_[INJ|REG|AWD]() and callback functions

      • Data transfer by DMA mode: using HAL_ADC_[INJ|REG|MM]_StartConv_DMA()

      • Note: IT and DMA mode can be used with optional interruptions (analog watchdog, …) using functions HAL_ADC_[INJ|REG|MM]_StartConv_IT_Opt(), HAL_ADC_[INJ|REG|MM]_StartConv_DMA_Opt()

  • HAL ADC operation steps:

    1. Activate ADC using HAL_ADC_Start()

    2. Perform ADC calibration using HAL_ADC_Calibrate()

    3. Start ADC conversions using functions HAL_ADC_[INJ|REG|MM]_StartConv…() (refer to list above)

    4. Process conversion data using HAL_ADC_[INJ|REG|MM]_GetValue(), IRQ handler and callback functions, DMA buffers

    5. Stop ADC conversions using functions HAL_ADC_[INJ|REG|MM]_StopConv…() Note: With trigger SW start, conversions iterations without conversion stop operation is possible using function HAL_ADC_[INJ|REG|MM]_TrigNextConv().

    6. Deactivate ADC using HAL_ADC_Stop()

Callback registration

When the compilation flag USE_HAL_ADC_REGISTER_CALLBACKS is set to 1, functions HAL_ADC_Register…Callback() allow to register following callbacks:

• HAL_ADC_ErrorCallback() : ADC error callback

• HAL_ADC_REG_EndOfSamplingCallback() : ADC group regular end of sampling phase callback

• HAL_ADC_REG_UnitaryConvCpltCallback() : ADC group regular end of unitary conversion callback

• HAL_ADC_REG_SequenceConvCpltCallback() : ADC group regular end of sequence conversions callback

• HAL_ADC_REG_DataTransferHalfCallback() : ADC group regular conversion data buffer half transfer callback (under condition of USE_HAL_ADC_DMA activated)

• HAL_ADC_REG_DataTransferCpltCallback() : ADC group regular conversion data buffer transfer complete callback (under condition of USE_HAL_ADC_DMA activated)

• HAL_ADC_REG_DataTransferStopCallback() : ADC group regular conversion data transfer abort callback (under condition of USE_HAL_ADC_DMA activated)

• HAL_ADC_INJ_UnitaryConvCpltCallback() : ADC group injected end of unitary conversion callback

• HAL_ADC_INJ_SequenceConvCpltCallback() : ADC group injected end of sequence conversions callback

• HAL_ADC_AnalogWD_OutOfWindowCallback() : ADC analog watchdog out of window event callback

When the compilation flag USE_HAL_ADC_REGISTER_CALLBACKS is set to 0 or not defined, the callback registration feature is not available and all callbacks are set to the corresponding weak functions.